The shot-blasting machine basically comprises a cabinet, a rotary drum having holes, and a centrifugal shooting machine. The rotary drum is located inside the cabinet and moves forward and backward around the horizontal shaft through the positions for feeding products to be processed, for processing them, and for taking out them. The shaft passes through the central axis of the rotary drum. The cabinet comprises a cover for shutting the opening that is used to feed the materials to be processed and to take them out.
In conventional shot-blasting machines the cover of the cabinet uses double sliding doors or double swinging doors. For these double sliding doors or double swinging doors additional spaces (dead spaces) for moving the doors have been required. Further, a driving force for the doors, in addition to a driving force for the rotary drum, has been required (see paragraph 0002 of Japanese Patent Laid-open Publication No. H08-126959). Thus in Japanese Patent Laid-open Publication No. H08-126959 the applicant proposed the following shot-blasting machine, wherein the dead spaces that were used for the cover for shutting the opening for feeding and taking out works were eliminated, and wherein the cover was opened and closed by the same driver as that for the rotary drum.
Below, claim 1 of that patent application is referred to, and FIG. 1 is appended to the present application also as FIG. 1. Incidentally, the numbers in FIG. 1 are unrelated to those in FIGS. 2 to 15.
“A shot-blasting machine using a rotary drum,
wherein a cabinet 2 is formed in the front side to project like a semicircle 3 in a view from a side,
wherein a centrifugal shooting machine 1 is provided on the back and upper side of the cabinet 2, the centrifugal shooting machine being directed forward and downward,
wherein a vertical and long arc-shaped opening 4 is formed on the semicircle 3,
wherein a semicircular sliding cover 7 is provided to be engaged with the arc-shaped opening 4 through a labyrinth seal, the semicircular sliding cover 7 moving forward and backward around an axis, and
wherein, when the sliding cover 7 shuts the arc-shaped opening 4, a rotary drum 13 that has a U-shaped section is provided on the inner face of the sliding cover 7, a leading end of the rotary drum being inclined toward the centrifugal shooting machine 1.”
However, since the proposed shot-blasting machine used a labyrinth seal, the structure was complicated, a high degree of accuracy was required, and the cost tended to be high.